Dry-method positive electrode sheet, method for manufacturing the same, and lithium ion battery

Abstract

The application belongs to the technical field of lithium ion batteries, and particularly relates to a dry-method positive electrode sheet, a preparation method thereof and a lithium ion battery. The dry-method positive electrode sheet comprises a positive electrode diaphragm, a positive electrode current collector layer arranged on one side of the positive electrode diaphragm, and a positive electrode solid-state electrolyte diaphragm layer arranged on the other side of the positive electrode diaphragm. The positive electrode diaphragm is prepared by a dry method. The current collector layer is formed by vacuum evaporation or magnetron sputtering of conductive material on the surface of one side of the positive electrode diaphragm. The solid-state electrolyte diaphragm layer is formed by vacuum evaporation or magnetron sputtering of solid-state electrolyte material on the surface of the other side of the positive electrode diaphragm. After drying, the dry-method positive electrode sheet is subjected to calendering and slitting. The dry-method electrode sheet prepared by the application does not need an additional conductive coating. The thickness of the solid-state electrolyte diaphragm layer is uniform and controllable. The interface contact problem between the solid-state electrolyte diaphragm and the active material diaphragm is solved. The energy density of the lithium ion battery is improved, and the electrochemical performance is improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a dry-process positive electrode sheet, its preparation method, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and other fields due to their outstanding advantages such as high energy density, long cycle life, and environmental friendliness.

[0003] As a core component of lithium-ion batteries, the electrode's manufacturing process directly determines the battery's performance and cost. Traditional lithium-ion battery electrodes generally employ a wet coating process. This process involves dispersing active materials, conductive agents, and binders in organic solvents such as NMP to form a slurry, which is then coated onto the current collector surface and dried at high temperature followed by roll forming. However, the wet process has significant drawbacks: firstly, the extensive use of organic solvents not only causes severe environmental pollution but also significantly increases production costs; secondly, the slurry drying process is prone to problems such as uneven distribution of active materials and difficulty in precisely controlling the pore structure, limiting further improvements in battery energy density and cycle performance.

[0004] Therefore, dry electrode fabrication technology has gradually attracted attention due to its advantages such as low cost, high load capacity, and environmental friendliness, especially in the field of solid-state batteries. However, existing dry electrode fabrication technologies still have some problems.

[0005] 1) Complex process and easy loss of conductivity: Traditional dry electrode requires coating conductive adhesive on positive and negative current collectors, which is a complex process that not only prolongs the preparation process but also increases the interfacial resistance and reduces the conductivity between the active particles and the current collector.

[0006] 2) Limitations of binder performance: The binders of conductive coatings often cannot simultaneously meet the requirements of high temperature resistance, electrolyte corrosion resistance and wide voltage window compatibility, resulting in battery capacity decay and decreased cycle stability.

[0007] 3) Poor electrode structure consistency: During the high-pressure forming process such as roll forming, cracks and peeling are prone to occur between the current collector and the active material under high pressure, resulting in poor electrode consistency.

[0008] 4) Limited energy density: The introduction of conductive coating increases the electrode thickness, and the coating thickness is difficult to control precisely, resulting in a decrease in the energy density of the battery.

[0009] This application addresses the aforementioned issues and is of great significance for overcoming the technical bottlenecks of existing dry process technologies, simplifying the process flow, improving the energy density and cycle stability of lithium-ion batteries, and promoting the industrial application of dry electrode technology. Summary of the Invention

[0010] In view of this, this application provides a dry-process positive electrode sheet, its preparation method, and a lithium-ion battery. Conductive materials and solid electrolytes are deposited onto the dry-process electrode film by vacuum evaporation or magnetron sputtering, respectively. This method eliminates the need for an additional conductive coating on the current collector, and the resulting solid electrolyte separator layer has a uniform and controllable thickness, solving the interfacial contact problem between the solid electrolyte film and the active material film. The dry-process electrode prepared by this method improves the energy density and electrochemical performance of the lithium-ion battery.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, this application provides a dry-process positive electrode sheet, comprising a positive electrode membrane, a positive electrode current collector layer disposed on one side of the positive electrode membrane, and a positive electrode solid electrolyte separator layer disposed on the other side of the positive electrode membrane.

[0012] Furthermore, the thickness of the positive electrode current collector layer is 0.5-3 μm, preferably 1 μm; the thickness of the positive electrode solid electrolyte membrane layer is 1-2 μm, preferably 1 μm.

[0013] Furthermore, the positive electrode membrane includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent; the mass ratio of the positive electrode active material to the positive electrode binder to the positive electrode conductive agent is (93-98):(0-2):(1-3).

[0014] Furthermore, the positive electrode active material includes one or more of the following: binary layered oxides, ternary layered oxides, spinel oxides, olivine phosphates, and fluorinated polyanionic compounds. Preferably, the positive electrode conductive agent includes one or more of graphite, graphene, carbon nanotubes, powdered conductive carbon nanotubes, conductive carbon black, hard carbon, and soft carbon. Preferably, the positive electrode binder includes one or more of carboxymethyl cellulose, styrene-butadiene rubber, polyacrylate, polytetrafluoroethylene, polyvinylidene fluoride, nitrile rubber, polyamide, polyvinyl alcohol, polyethyleneimine, and polyimide.

[0015] Furthermore, the positive electrode current collector layer includes one or more of carbon-based materials, metallic materials, and alloy materials; preferably, the carbon-based materials include graphite, graphene, carbon nanotubes, hard carbon, and soft carbon; the metallic materials include copper, silver, gold, and aluminum; and the alloy materials include copper alloys, aluminum alloys, and silver alloys.

[0016] Furthermore, the positive electrode solid electrolyte layer includes one or more of the following: sulfide solid electrolyte, oxide solid electrolyte, halide solid electrolyte, and polymer solid electrolyte. Preferably, the sulfide solid electrolyte comprises Li7P3S 11 Or Li10 GeP2S 12 ; Preferably, the oxide solid electrolyte includes lithium lanthanum zirconate LLZO, lithium lanthanum titanate LLTO, or lithium titanate Li2TiO3; Preferably, the halide solid electrolyte includes Li3YCl6, Li3YBr6, Li2ZrCl6, LiInCl3 or Li3HoCl6; Preferably, the polymer solid electrolyte includes one or more of polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA).

[0017] A second aspect of this application provides a method for preparing the above-mentioned dry-process positive electrode sheet, comprising the following steps: S1. The positive electrode film is prepared using a dry method; S2. The current collector material is deposited on one side surface of the positive electrode film by vacuum evaporation or magnetron sputtering to form a current collector layer; S3. Solid electrolyte material is deposited onto the other side of the positive electrode membrane by vacuum evaporation or magnetron sputtering to form a solid electrolyte membrane layer; S4. The composite dry-process positive electrode sheet is dried and then rolled and slit.

[0018] Furthermore, the vacuum evaporation includes resistance evaporation, electron beam evaporation, laser evaporation, dual-source or multi-source evaporation, and reactive evaporation, preferably resistance evaporation or electron beam evaporation. In the resistance evaporation, the resistance heating source current is >20A and the voltage is <10V; in the electron beam evaporation, the current is 0.1-1.5A and the voltage is >4KV; the vacuum degree of the vacuum evaporation is not less than 10 kV. -5 Pa.

[0019] Preferably, the magnetron sputtering includes DC magnetron sputtering, MF magnetron sputtering, and RF magnetron sputtering.

[0020] A third aspect of this application provides a lithium-ion battery, comprising a dry-process positive electrode sheet or a dry-process positive electrode sheet prepared by the above-described method, and a dry-process negative electrode sheet. The dry-process negative electrode sheet comprises a negative electrode film, a negative electrode current collector layer, and a negative electrode solid electrolyte separator layer. The negative electrode film comprises a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent. Preferably, the mass ratio of the negative electrode active material: negative electrode binder: negative electrode conductive agent is (93-98):(0-2):(1-3). Preferably, the negative electrode active material includes one or more of carbon-based negative electrodes, silicon-based negative electrodes, germanium-based negative electrodes, and oxide negative electrodes.

[0021] Furthermore, the negative electrode film is prepared by a dry method; the negative electrode current collector layer is formed by depositing conductive material on one side surface of the negative electrode film through vacuum evaporation or magnetron sputtering; the negative electrode solid electrolyte membrane layer is formed by depositing solid electrolyte material on the other side surface of the negative electrode film through vacuum evaporation or magnetron sputtering.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention relates to a composite electrode obtained by vacuum evaporation or magnetron sputtering separately depositing conductive materials and solid electrolytes onto a dry electrode film, and its preparation method, which has the following advantages: (1) Simplified preparation process: There is no need to prepare the current collector of the dry electrode separately. The conductive material can be directly plated on the dry film as the current collector, which significantly reduces the production cost and solves the problems of cracking and poor adhesion in the process of combining the dry electrode and the current collector.

[0023] (2) Process innovation: On the one hand, vacuum evaporation or magnetron sputtering technology is used to prepare current collectors, which makes the current collectors thinner and effectively improves the energy density of the battery; on the other hand, solid electrolytes are deposited on dry membranes through vacuum evaporation or magnetron sputtering technology to form electrolyte membranes with uniform and controllable thickness, realizing the integrated composite of "electrode-current collector-separator".

[0024] (3) Stable structure: It does not involve the application of conductive adhesive coating, thus avoiding the problem that conductive coating binder cannot simultaneously meet the requirements of high temperature resistance, electrolyte resistance, and wide voltage window, thereby expanding the application range of the battery; (4) Precisely match performance requirements: broaden application scenarios: the thickness of current collector and electrolyte membrane can be precisely controlled to achieve differentiated manufacturing and meet the performance requirements of different batteries. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the dry electrode sheet structure according to an embodiment of this application. Wherein, 1. dry electrode sheet, 2. current collector layer, 3. solid electrolyte membrane layer. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0027] Comparative Example 1: Step 1: Mix NCM811 (lithium nickel cobalt manganese oxide), PVDF (polyvinylidene fluoride), CNTs (carbon nanotubes), and SP (conductive carbon black) at room temperature in a mass ratio of 97:1:0.5:1.5 until homogeneous. The slurry viscosity should be 7000-8000 cp and the fineness should be <15μm to obtain the positive electrode slurry. Mix graphite, carboxymethyl cellulose, styrene-butadiene rubber, and conductive carbon black at room temperature in a mass ratio of 97:1:1:1 until homogeneous. The slurry viscosity should be 2000-3000 cp and the fineness should be <30μm to obtain the negative electrode slurry. Step 2: Evenly coat the positive electrode slurry onto a 10μm aluminum foil, with a positive electrode surface density of 35mg / cm² and a compaction of 3.5g / cm². 3 The negative electrode slurry was uniformly coated onto a 6μm copper foil. The negative electrode mass ratio was Cr:CMC:SBR:SP = 97:1:1:1, and the negative electrode areal density was 20 mg / cm³. 2 Compacted to 1.69 g / cm³ 3 ; Step 3: Assemble the above positive and negative electrode sheets and separator into a battery cell using a 12μm base film, with a rated capacity of 5000mAh.

[0028] Comparative Example 2: Step 1: Mix NCM811 (lithium nickel cobalt manganese oxide), PTFE (polytetrafluoroethylene), CNTs (carbon nanotubes), and SP (conductive carbon black) evenly at a mass ratio of 97:1:0.5:1.5 at a temperature below 15°C. Mix graphite, PTFE, and SP (conductive carbon black) evenly at a mass ratio of 98:1:1 at a temperature below 15°C. Step 2: Adjust the mixing temperature to 120℃ and the shear force to 6 MPa for prefiberization until the material becomes cotton-like; Step 3: Place the mixture in a roller mill with a roller temperature of 200 degrees Celsius and a roller pressure of 10 MPa, and shear it through multiple rollers to form positive and negative electrode films; Step 4: Thermally laminate the positive and negative electrode films with special base-coated aluminum foil and base-coated copper foil respectively at a lamination temperature of 80℃ to form positive and negative electrode sheets, wherein the areal density of the positive electrode is 35 mg / cm³. 2 Compacted to 3.6 g / cm³ 3 Negative electrode surface density 20 mg / cm³ 2 Compacted to 1.75 g / cm³ 3 The thicknesses of the positive and negative electrode undercoating foils are 20 μm and 16 μm, respectively; Step 5: Assemble the above positive and negative electrode sheets into a battery cell (solid electrolyte is LLZO), with a rated capacity of 5000mAh (0.2C).

[0029] Example 1: Dry cathode preparation: S1. Preparation of dry-process positive electrode film: S101. Mix NCM811 (lithium nickel cobalt manganese oxide), PTFE (polytetrafluoroethylene), CNTs (carbon nanotubes), and SP (conductive carbon black) uniformly at a mass ratio of 97:1:0.5:1.5 at a temperature below 15°C. Circulate cooling water to ensure that the temperature of the dispersion chamber is less than 10°C, ensuring that the PTFE powder, main material, and conductive agent are uniformly dispersed and do not become fibrous. S102. Turn off the cooling water, adjust the temperature of the dispersion chamber to 120℃, and the shear force to 6Mpa to carry out prefiberization until the material is in the form of cotton wool; S103. The mixture is placed in a roller mill with a roller temperature of 200 degrees Celsius, a roller pressure of 10 MPa, and a belt speed of 5 m / min, and sheared into a positive electrode film through multiple rollers; wherein the positive electrode areal density is 35 mg / cm³. 2 Compacted to 3.6 g / cm³ 3 ; S104. Vacuum preheating is used to remove impurities such as air and moisture from the surface and pores of the dry cathode film; S2. Preparation of the current collector layer by vacuum evaporation: S201. Place the dry-process positive electrode film prepared in S1 into a vacuum chamber with a vacuum level of 1×10⁻⁶. -5 Pa.

[0030] S202. A resistance heating source with a current of 50A and a voltage of 5V is used to heat aluminum foil or copper foil (purity > 99.99%) to a sufficiently high temperature (1200℃-1400℃) through a heating evaporator, so that its atoms gradually sublimate and deposit on the surface of the dry positive electrode film to form a current collector layer.

[0031] S203. Control the temperature during the vacuum evaporation process to 80-120℃ and the time to 30-60min. Control the evaporation rate in steps, i.e., evaporation at 0.1nm / s for 30min, 10nm / s for 20min, and 50nm / s for 10min, so that the aluminum foil is evenly distributed on the surface of the dry film to form a current collector layer with a thickness of 1μm.

[0032] S3. Preparation of solid electrolyte membrane layer by magnetron sputtering: S301. Use lithium-rich LLZO ceramic targets to mount the targets onto the RF magnetron sputtering cathode, ensuring good backplane cooling and electrical connection.

[0033] S302. The positive electrode sheet prepared in S2 is placed in a vacuum chamber as a substrate, and the vacuum level is adjusted to 9.0 × 10⁻⁶. -5 Pa or above S303. Introduce high-purity (99.999%) argon (Ar) as the working gas, and adjust the flow rate to stabilize the working gas pressure at 0.5-2.0 Pa.

[0034] S304. Cover the substrate with a baffle, turn on the RF power supply (13.56 MHz), and perform pre-sputtering for 15-30 minutes at a low power of 20W. Clean the target surface to remove any adsorbed gases and surface impurities to stabilize the sputtering process.

[0035] S306. Adjust the RF power to 80W, argon gas pressure to 0.8Pa, substrate temperature to 80℃, substrate bias voltage to -20V, deposit for 30-120min to form a dense LLZO film of 1μm and then perform annealing treatment.

[0036] Dry anode preparation: S1. Preparation of dry-process negative electrode film: Graphite, PTFE (polytetrafluoroethylene), and SP (conductive carbon black) are mixed uniformly at a mass ratio of 98:1:1 at a temperature below 15°C. The remaining preparation methods are the same as for the dry-process positive electrode film. The film is then sheared into a negative electrode sheet using a multi-roller shearing process, with a negative electrode areal density of 20 mg / cm³. 2 Compacted to 1.75 g / cm³ 3 .

[0037] S2. The current collector layer is formed on one side of the negative electrode film by vacuum evaporation and the solid electrolyte membrane layer is formed on the other side of the negative electrode film by magnetron sputtering, which is consistent with the dry method for positive electrode film processing.

[0038] Lithium-ion battery cell manufacturing: S1. Dry the composite dry positive and negative electrodes at 120°C for 4 hours in a vacuum drying oven.

[0039] S2. The dried positive and negative electrodes are calendered in a calender at a width pressure of 0.2-0.5 t / cm.

[0040] S3. Cut and shear the rolled dry positive and negative electrodes into the desired positive and negative electrode sheets.

[0041] S4. Assemble the prepared composite positive and negative electrode sheets into a battery cell with a rated capacity of 5000mAh (0.2C).

[0042] Example 2: Dry-process positive electrode film and dry-process negative electrode film preparation: S1. Preparation of dry-process positive electrode film and dry-process negative electrode film: S101. NCM811 (lithium nickel cobalt manganese oxide), PVDF (polyvinylidene fluoride), CNTs (carbon nanotubes), and SP (conductive carbon black) are mixed uniformly at room temperature according to a mass ratio of 97:1:0.5:1.5, resulting in a slurry viscosity of 7000-8000cp and a fineness of <15μm, to obtain the positive electrode slurry; graphite, carboxymethyl cellulose, styrene-butadiene rubber, and conductive carbon black are mixed uniformly at room temperature according to a mass ratio of 97:1:1:1, resulting in a slurry viscosity of 2000-3000cp and a fineness of <30μm, to obtain the negative electrode slurry; S102. The positive electrode slurry and negative electrode slurry are respectively coated on a polyethylene terephthalate (PET) separation membrane to form a positive electrode layer and a negative electrode layer, with a positive electrode areal density of 35 mg / cm³. 2 Compacted to 3.55 g / cm³ 3 Negative electrode surface density 20 mg / cm³ 2 Compacted to 1.69 g / cm³ 3 .

[0043] S103. The positive electrode layer, negative electrode layer and PET film are separated by cold pressing at a pressure of 0.5 MPa to form dry positive and negative electrode films.

[0044] S104. Vacuum preheating is used to remove air, moisture and other impurities from the surface and pores of the dry-process positive and negative diaphragms; S2. Preparation of the current collector layer by vacuum evaporation: Same preparation method as in Example 1 S3. Preparation of solid electrolyte membrane layer by magnetron sputtering: Same as Example 1.

[0045] S4. Cell fabrication: Same as Example 1.

[0046] Example 3: S1. Preparation of dry-process positive electrode film and dry-process negative electrode film: Same as Example 1.

[0047] S2. Current collector layers are prepared on dry-process positive and negative electrode films by magnetron sputtering: S201. Place the dry-process positive electrode film or dry-process negative electrode film prepared in S1 into a vacuum chamber with a vacuum degree of 1×10⁻⁶. -5 Pa.

[0048] S202. Use a high-purity (99.99% or higher) copper or aluminum target and mount the target on the DC magnetron sputtering cathode to ensure good backplane cooling and electrical connection.

[0049] S203. High-purity (99.999%) argon (Ar) gas is introduced into the chamber as the working gas, and a constant working pressure (usually 0.3-1.0 Pa) is maintained by a pressure controller.

[0050] S204. Turn on the DC power supply to generate glow discharge and form plasma. Cover the substrate with a baffle and perform a short-term (5-10 min) pre-sputtering to clean the target surface, remove any adsorbed gases and surface impurities, and stabilize the sputtering process.

[0051] S205, Remove the baffle and begin formal deposition. Sputtering power is 1-10 W / cm². 2 Adjustable flow rate to stabilize working gas pressure at 0.5-2.0 Pa, adjustable substrate temperature at 25-100℃, deposition time 5-20 min, forming a dense metallic conductive layer of 100-2000 nm as positive and negative electrode current collectors.

[0052] S3. Solid electrolyte membrane layer is prepared on dry-process positive and negative electrode films by magnetron sputtering: Same preparation method as in Example 1 S4. Cell fabrication: The preparation method is the same as in Example 1.

[0053] Example 4: S1. Preparation of dry-process positive electrode film and dry-process negative electrode film: Same as Example 1.

[0054] S2. Current collector layers are prepared on dry-process positive and negative electrode films by vacuum evaporation: Same as Example 1.

[0055] S3. Solid electrolyte membrane layer is prepared on dry-process positive and negative electrode films by vacuum evaporation: S301. Place high-purity, dry LiCl and YCl3 powders into two separate tantalum or tungsten boats, respectively. Place the dry-processed positive or negative electrode film prepared in S1 into a vacuum chamber with a vacuum degree of 1×10⁻⁶. -5 Pa.

[0056] S302. Cover the substrate with a baffle. Slowly preheat the two evaporation sources (below the evaporation temperature of 700°C) to remove residual moisture and gas adsorbed in the raw material.

[0057] S303. First, test the evaporation rates of LiCl source and YCl3 source under different heating currents (monitored by a quartz crystal film thickness gauge). S304. According to the calibration curve, make the evaporation rate ratio of LiCl and YCl3 3:1.

[0058] S305. Remove the baffle, turn on the heating power supply of both sources at the same time, and maintain it at the preset current value to perform co-evaporation deposition, forming a 1μm dense Li3YCl6 thin film and then performing annealing treatment.

[0059] S4. Cell fabrication: Same as Example 1.

[0060] Test results: The peel force test for this application was performed using a universal tensile tester with 3M tape, 40mm wide, peeled at 180°, in accordance with national standards.

[0061] The performance of the dry-processed electrodes prepared in Examples 1-4, Comparative Examples 1 and 2 was tested, and the test results are shown in Table 1.

[0062] Table 1 Electrode adhesion and interfacial resistance test

[0063] As shown in Table 1 above, compared to the traditional wet coating process in Comparative Example 1 or the dry hot-pressing composite process in Comparative Example 2, direct vacuum evaporation or magnetron sputtering significantly improved interfacial adhesion, increasing the bonding strength by approximately 34%. The interfacial resistivity of Examples 1-4 was significantly better than that of Comparative Examples 1 and 2. This further verifies that depositing conductive materials and solid electrolytes onto the dry electrode film via vacuum evaporation or magnetron sputtering solves the interfacial contact problem between the solid electrolyte film and the active material film. Therefore, the performance of the dry electrode film used for both positive and negative electrodes, with current collector layers and solid electrolyte layers formed on both sides of the electrode film through evaporation or magnetron sputtering, is superior to that of the untreated electrode film.

[0064] The dry-processed electrodes prepared in Examples 1-4, Comparative Examples 1 and 2 were used to fabricate lithium-ion batteries and their performance was tested. The test results are shown in Table 2.

[0065] Table 2 Battery DCIR, Rate, and Cycle Tests

[0066] As shown in Table 2 above, compared to the traditional wet coating process in Comparative Example 1 or the dry hot-pressing composite process in Comparative Example 2, the cells prepared directly by vacuum evaporation or magnetron sputtering exhibit significantly improved performance. Specifically, the DC internal resistance (DCIR) measured at 50% SOC (DCIR@50%SOC), which is the total resistance that impedes the passage of DC current when the battery's remaining capacity is half, is significantly reduced in Examples 1-4, thereby improving the battery's fast charging and discharging capabilities and reducing heat generation during charging and discharging. Example 1 shows significantly better 2C capacity retention than Comparative Examples 1 and 2. After 500 high-temperature cycles, Example 1-4 show better capacity retention than Comparative Examples 1 and 2.

[0067] The above description is merely an example of the embodiments of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A dry-process positive electrode, characterized in that, It includes a positive electrode membrane, a positive electrode current collector layer disposed on one side of the positive electrode membrane, and a positive electrode solid electrolyte membrane layer disposed on the other side of the positive electrode membrane.

2. The dry-process positive electrode sheet according to claim 1, characterized in that, The thickness of the positive electrode current collector layer is 0.5-3 μm, preferably 1 μm; the thickness of the positive electrode solid electrolyte membrane layer is 1-2 μm, preferably 1 μm.

3. The dry-process positive electrode sheet according to claim 1, characterized in that, The positive electrode membrane includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent; the mass ratio of the positive electrode active material: positive electrode binder: positive electrode conductive agent is (93-98):(0-2):(1-3).

4. The dry-process positive electrode sheet according to claim 3, characterized in that, The positive electrode active material includes one or more of the following: binary layered oxides, ternary layered oxides, spinel oxides, olivine phosphates, and fluorinated polyanionic compounds. Preferably, the positive electrode conductive agent includes one or more of graphite, graphene, carbon nanotubes, powdered conductive carbon nanotubes, conductive carbon black, hard carbon, and soft carbon. Preferably, the positive electrode binder includes one or more of carboxymethyl cellulose, styrene-butadiene rubber, polyacrylate, polytetrafluoroethylene, polyvinylidene fluoride, nitrile rubber, polyamide, polyvinyl alcohol, polyethyleneimine, and polyimide.

5. The dry-process positive electrode sheet according to claim 1, characterized in that, The positive electrode current collector layer comprises one or more of carbon-based materials, metallic materials, and alloy materials; preferably, the carbon-based materials include graphite, graphene, carbon nanotubes, hard carbon, and soft carbon; the metallic materials include copper, silver, gold, and aluminum; and the alloy materials include copper alloys, aluminum alloys, and silver alloys.

6. The dry-process positive electrode sheet according to claim 1, characterized in that, The positive electrode solid electrolyte layer includes one or more of the following: sulfide solid electrolyte, oxide solid electrolyte, halide solid electrolyte, and polymer solid electrolyte; Preferably, the sulfide solid electrolyte comprises Li7P3S 11 Or Li 10 GeP2S 12 ; Preferably, the oxide solid electrolyte includes lithium lanthanum zirconate LLZO, lithium lanthanum titanate LLTO, or lithium titanate Li2TiO3; Preferably, the halide solid electrolyte includes Li3YCl6, Li3YBr6, Li2ZrCl6, LiInCl3 or Li3HoCl6; Preferably, the polymer solid electrolyte includes one or more of polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA).

7. A method for preparing a dry-process positive electrode according to any one of claims 1-6, characterized in that, Includes the following steps: S1. The positive electrode film is prepared using a dry method; S2. The current collector material is deposited on one side surface of the positive electrode film by vacuum evaporation or magnetron sputtering to form a current collector layer; S3. Solid electrolyte material is deposited onto the other side of the positive electrode membrane by vacuum evaporation or magnetron sputtering to form a solid electrolyte membrane layer; S4. The composite dry-process positive electrode sheet is dried and then rolled and slit.

8. The preparation method according to claim 7, characterized in that, The vacuum evaporation includes resistance evaporation, electron beam evaporation, laser evaporation, dual-source or multi-source evaporation, and reactive evaporation, preferably resistance evaporation or electron beam evaporation. In resistance evaporation, the resistance heating source current is >20A and the voltage is <10V; in electron beam evaporation, the current is 0.1-1.5A and the voltage is >4KV; the vacuum degree of the vacuum evaporation is not less than 10 kV. -5 Pa. Preferably, the magnetron sputtering includes DC magnetron sputtering, MF magnetron sputtering, and RF magnetron sputtering.

9. A lithium-ion battery, characterized in that, The invention includes a dry-process positive electrode sheet as described in any one of claims 1-6 or a dry-process positive electrode sheet prepared by the preparation method described in any one of claims 7-8, and a dry-process negative electrode sheet. The dry-process negative electrode sheet comprises a negative electrode film, a negative electrode current collector layer, and a negative electrode solid electrolyte separator layer. The negative electrode film comprises a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent. Preferably, the mass ratio of the negative electrode active material: negative electrode binder: negative electrode conductive agent is (93-98):(0-2):(1-3). Preferably, the negative electrode active material includes one or more of carbon-based negative electrodes, silicon-based negative electrodes, germanium-based negative electrodes, and oxide negative electrodes.

10. The lithium-ion battery according to claim 9, characterized in that, The negative electrode film is prepared by a dry method; the negative electrode current collector layer is formed by depositing conductive material on one side of the negative electrode film by vacuum evaporation or magnetron sputtering; the negative electrode solid electrolyte membrane layer is formed by depositing solid electrolyte material on the other side of the negative electrode film by vacuum evaporation or magnetron sputtering.

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